215/60R18 vs 195/65R18
Going from one to the other changes the overall height by -0.6 %. That is inside the 3% band, so it fits and the speedometer stays close.
Side by side
| Measure | 215/60R18 | 195/65R18 | Change |
|---|---|---|---|
| Overall height | 28.2" | 28.0" | -0.6 % |
| Sidewall | 5.08" | 4.99" | -1.7 % |
| Section width | 215 mm | 195 mm | -9.3 % |
| Circumference | 88.5" | 87.9" | -0.6 % |
| Revs per mile | 716 | 721 | +0.6 % |
| Axle height | 14.08" | 13.99" | -2.3 mm |
| Approved rim width | 6–8" | 5.5–7" | overlap 6–7" |
Both are approved on a rim 6" to 7" wide. If yours is in that band, this is a tire change and nothing else.
What the speedometer will say
Calibrated for 215/60R18. Fit 195/65R18 and the needle stops telling the truth.
| Needle says | You are doing | Out by |
|---|---|---|
| 30 mph | 29.8 mph | -0.2 |
| 50 mph | 49.7 mph | -0.3 |
| 70 mph | 69.6 mph | -0.4 |
| 90 mph | 89.4 mph | -0.6 |
The odometer drifts with it. Ten thousand miles on the dial are really 9,937 on the road, so it over-counts by 63. At a true 70 mph the first turns 836 times a minute, the second 841.